The present invention relates to a control system for changing over the rotational direction of a two cycle internal combustion engine, according to a reverse command in order to switch the running direction of a running equipment (vehicle) such as a small size vehicle driven by the engine.
A small size two cycle internal combustion engine is generally used as a drive source for a running equipment such as a scooter, a snow mobile, and a buggy car which places importance on simplicity or convenience. Since this type of running equipment is required to be small, light weight, and inexpensive, a stepless transmission of a centrifugal clutch type (automatic power transmission means) which does not include a back gear is adopted as a power transmission means for transmitting an output of the internal combustion engine to a driving wheel of a running equipment.
Since a running equipment employing a transmission including no back gear cannot go backward by switching the transmission, it is necessary to lift the entire running equipment in order to change the direction when it is required to reverse a running direction in a narrow space, thereby it is highly deteriorated in operability.
In a case of operating a snow mobile, since it cannot go backward, it is difficult to get out of the situation when its tip becomes buried in the snow.
In order to switch the running direction of a vehicle employing a transmission having no back gear as described above, it may be thought to take a method by which the rotative direction of an internal combustion engine is reversed.
Specifically, since it is possible to rotate in both forward and reverse directions in a two cycle internal combustion engine and a normal operation can be executed even in the forward rotation or the reverse rotation, when a two cycle internal combustion engine is employed as an engine for driving a vehicle, it is possible to switch the running direction of the vehicle by switching the rotative direction of the internal combustion engine.
In a two cycle internal combustion engine, when an ignition position (a rotative angle position of a rotary crankshaft of the engine at the time of igniting the engine) is advanced to an excessively advanced position (a position further advanced than an allowable maximum advanced position of the ignition position at the time of steady operation) in the state in which the engine speed is sufficiently reduced by reducing the injection quantity and/or stopping the injection of fuel, it is possible to reverse the rotative direction of the engine by pushing back a piston which is moving to a top dead center inside a cylinder. Also, by setting the ignition position of the engine at a position suitable for normally maintaining the rotation to the reverse direction after the reversion of the rotative direction of the engine is confirmed, the operation of the internal combustion engine can be normally maintained in a state in which the rotative direction is reversed.
As shown in Japanese Patent Application Laid Open No. 11-82270, Japanese Patent Application Laid Open No. 11-93718, and Japanese Patent Application Laid Open No. 11-93719, a control system for an internal combustion engine is proposed, which the rotative direction of a two cycle internal combustion engine can be reversed according to a command of a driver in order to switch the running direction of a running equipment. In these proposed control systems, a reverse command which commands reversing the rotative direction of the internal combustion engine is generated by letting a driver manually operate a switch so as to reduce the injection quantity or stop the injection of fuel responding to the reverse command, and the engine speed of the internal combustion engine is reduced. Then, when the engine speed of the internal combustion engine is sufficiently reduced, the rotative direction of the engine is reversed by excessively advancing the ignition position of the engine to a further advanced position sufficiently beyond the top dead center of a piston.
However, even when the control described above is executed, reversing the rotative direction fails although it is rare. When reversing the rotative direction fails, if the driver executes an operation of accelerating the engine without knowing the failure, it is very dangerous since the running equipment suddenly runs in the direction opposite to the direction that the driver intends.
The present applicants have previously proposed a control system for an internal combustion engine having a means which may inform which direction the engine actually rotates and inform that reversing is failed after giving a reverse command as shown in Japanese Patent Application Laid Open No. 2000-97094. When this type of informative means is employed, a situation in which an engine is accelerated in a state in which a running equipment runs in the direction opposite to that a driver intends can be avoided, thereby bringing a preferable condition.
However, even when a control system for an internal combustion engine has such informative means, a driver may drive without actually confirming the rotative direction of the engine which the informative means informs. A driver may erroneously recognize the rotative direction of the engine which the informative means informs. A driver may not be able to confirm an actual rotative direction of the engine since an indicator or the like that is an informative means does not work well even though a reverse process is normally executed. In any cases, if an engine is rotated so that the running direction of a running equipment becomes different from the direction that a driver intends, driving is not safely executed.
The present invention has been made in view of the foregoing disadvantages of the prior. Accordingly, it is an object of the present invention to provide a control system for an internal combustion engine which can avoid a running equipment from running in the direction that a driver does not intend in the case in which reversing the rotative direction of the internal combustion engine is failed although a reverse command is given.
According to the present invention, a control system for an internal combustion engine is provided, which comprises a reverse command generating means generating a reverse command for switching a running direction of a running equipment driven by a two cycle internal combustion engine, a reverse processing means executing a reverse process necessary for reversing a rotative direction of the internal combustion engine based on the reverse command which is generated from the reverse command generating means, a rotative direction detection means generating rotation detection signals of which states are different at each time when the internal combustion engine is forwardly rotated and is reversely rotated and detecting the rotative direction of the internal combustion engine from a state of the rotation detection signal, a reverse failure determining means determining that reversing of the internal combustion engine is failed when the rotative direction detected by the rotative direction detection means does not correspond to the rotative direction commanded by the reverse command, and an internal combustion engine drive control means controlling the internal combustion engine so that running of the running equipment is prevented when the failure of the reversing of the rotative direction is determined by the reverse failure determining means.
In the present description, xe2x80x9crunning of the running equipment is preventedxe2x80x9d means that making the running equipment not move, or if it moves, making it move only slowly.
As described above, by preventing the running equipment from running when the failure of reversing the rotative direction of the engine is determined, the running equipment may be prevented from suddenly starting running in the direction that a driver does not intend in a case in which the driver executes an operation for accelerating the engine without noticing the failure of reversing the rotative direction of the engine.
In the present description, xe2x80x9crunning equipmentxe2x80x9d is employed in the meaning including all running vehicles such as a scooter, a snow mobile, a buggy car, and a motorboat which uses a two cycle internal combustion engine as a drive source.
The said internal combustion engine drive control means may be an engine drive stop means stopping the drive of the internal combustion engine by executing either stopping an ignition operation of the internal combustion engine or stopping a supply of fuel to the internal combustion engine or by executing both stopping an ignition operation of the internal combustion engine and stopping a supply of fuel to the internal combustion engine.
The said internal combustion engine drive control means may be means restricting the engine speed, which maintains the engine speed of the internal combustion engine at a value lower than a minimum engine speed necessary for becoming a state in which an automatic transmission can transmit the motive power of the internal combustion engine to the running equipment.
The said internal combustion engine drive control means may be means controlling the internal combustion engine so that running speed of the running equipment is restricted to a slow speed when the failure of the reversing of the rotative direction is determined by the reverse failure determining means.
The said internal combustion engine drive control means may be a transmission system control means controlling the transmission system so that transmission of the motive power from the internal combustion engine to the running equipment is terminated when the failure of the reversing of the rotative direction is determined by the reverse failure determining means.
When reversing the rotative direction of the engine is failed, if only the engine is stopped and/or only the running speed of the running equipment is restricted to a slow speed, it is likely that a driver does not realize the failure in reversing the rotative direction of the engine. Accordingly, it is preferable to provide an informative means informing the reverse failure when the reverse failure determining means determines the reverse failure.